package com.hmdp.service.impl;

import cn.hutool.core.util.BooleanUtil;
import cn.hutool.core.util.StrUtil;
import cn.hutool.json.JSONObject;
import cn.hutool.json.JSONUtil;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.hmdp.dto.Result;
import com.hmdp.entity.Shop;
import com.hmdp.mapper.ShopMapper;
import com.hmdp.service.IShopService;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.utils.CacheClient;
import com.hmdp.utils.RedisConstants;
import com.hmdp.utils.RedisData;
import com.hmdp.utils.SystemConstants;
import org.springframework.data.geo.Distance;
import org.springframework.data.geo.GeoResult;
import org.springframework.data.geo.GeoResults;
import org.springframework.data.redis.connection.RedisGeoCommands;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.domain.geo.GeoReference;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import javax.annotation.Resource;

import java.time.LocalDateTime;
import java.util.*;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;

import static com.hmdp.utils.RedisConstants.*;

/**
 * <p>
 *  服务实现类
 * </p>
 *
 * @author 虎哥
 * @since 2021-12-22
 */
@Service
public class ShopServiceImpl extends ServiceImpl<ShopMapper, Shop> implements IShopService {

    @Resource
    private StringRedisTemplate stringRedisTemplate;

    @Resource
    private CacheClient cacheClient;

    @Override
    public Result queryByid(Long id) {
        //解决缓存穿透
//        Shop shop = queryWithPassThrough(id);
//        Shop shop = cacheClient.queryWithPassThrough(CACHE_SHOP_KEY, id, Shop.class, /*id2 -> getById(id2)*/  this::getById, CACHE_SHOP_TTL, TimeUnit.MINUTES);

        //互斥锁解决缓存击穿
//        Shop shop = queryWithMutex(id);

        //逻辑过期解决缓存击穿
        Shop shop = cacheClient.queryWithLogicalExpire(CACHE_SHOP_KEY, id, Shop.class, this::getById, 20L, TimeUnit.MINUTES);


        if(shop == null){
            return Result.fail("店铺不存在！");
        }
        return Result.ok(shop);
    }

    public static final ExecutorService CACHE_REBUILD_EXECUTOR = Executors.newFixedThreadPool(10);

/*    public Shop queryWithLogicalExpire(Long id){//解决热点key的问题，所以这个业务不可能被穿透的
        String key = CACHE_SHOP_KEY + id;
        //1.从Redis查询商铺缓存
        String shopJson = stringRedisTemplate.opsForValue().get(key);
        //2.判断是否存在
        if (StrUtil.isBlank(shopJson)) {//ctrl + q,查看方法具体提示
            //3.存在，直接返回
            return null;
        }
        //4.命中，需要先把json反序列化为对象
        RedisData redisData = JSONUtil.toBean(shopJson, RedisData.class);
//        Object data = redisData.getData();
        JSONObject data =(JSONObject) redisData.getData();
        Shop shop = JSONUtil.toBean(data, Shop.class);
        LocalDateTime expireTime = redisData.getExpireTime();
        //5.判断是否过期
        if(expireTime.isAfter(LocalDateTime.now())){
            //5.1.未过期，直接返回店铺信息
            return shop;
        }
        //5.2 已过期，需要缓存重建
        //6.缓存重建
        //6.1获取互斥锁
        String lockKey = LOCK_SHOP_KEY + id;
        boolean isLock = tryLock(lockKey);
        //6.2判断是否获取锁成功
        if(isLock){
            //6.3 成功，开启独立线程实现缓存重建
            CACHE_REBUILD_EXECUTOR.submit(() -> {
                try {
                    //重建缓存
                    this.saveShop2Redis(id, 20L);
                } catch (Exception e) {
                    throw new RuntimeException(e);
                } finally {
                    //释放锁
                    unlock(lockKey);
                }
            });
        }
        //6.4 失败，获取过期的商铺信息
        return shop;
    }*/

/*    public Shop queryWithMutex(Long id){
        String key = CACHE_SHOP_KEY + id;
        //1.从Redis查询商铺缓存
        String shopJson = stringRedisTemplate.opsForValue().get(key);
        //2.判断是否存在
        if (StrUtil.isNotBlank(shopJson)) {//ctrl + q,查看方法具体提示
            //3.存在，直接返回
            return JSONUtil.toBean(shopJson, Shop.class);
        }
        //判断命中的是否是空值
        if(shopJson != null){
            //返回一个错误信息
            return null;
        }

        //4.实现缓存重建
        //4.1获取互斥锁
        String lockKey = "lock:shop:" + id;
        Shop shop = null;
        try {
            boolean isLock = tryLock(lockKey);
            //4.2判断是否成功
            if(!isLock){
                //4.3失败，休眠并重试
                Thread.sleep(50);
                return queryWithMutex(id);
            }
            //4.4成功，根据id查询数据库
            shop = getById(id);
            //模拟重建的延时
            Thread.sleep(200);
            //5.不存在
            if(shop == null){
                //将空值写入Redis
                stringRedisTemplate.opsForValue().set(key, "", CACHE_NULL_TTL, TimeUnit.MINUTES);
                return null;
            }
            //6.存在，写入Redis
            stringRedisTemplate.opsForValue().set(key,JSONUtil.toJsonStr(shop), CACHE_SHOP_TTL, TimeUnit.MINUTES);
        } catch (InterruptedException e) {
            throw new RuntimeException(e);
        } finally {
            //7.释放互斥锁
            unlock(lockKey);
        }

        //8.返回
        return shop;
    }*/


    public Shop queryWithPassThrough(Long id){
        String key = CACHE_SHOP_KEY + id;
        //1.从Redis查询商铺缓存
        String shopJson = stringRedisTemplate.opsForValue().get(key);
        //2.判断是否存在
        if (StrUtil.isNotBlank(shopJson)) {//ctrl + q,查看方法具体提示
            //3.存在，直接返回
            return JSONUtil.toBean(shopJson, Shop.class);
        }
        //判断命中的是否是空值
        if(shopJson != null){
            //返回一个错误信息
            return null;
        }

        //4.不存在，根据id查询数据库
        Shop shop = getById(id);
        //5.不存在
        if(shop == null){
            //将空值写入Redis
            stringRedisTemplate.opsForValue().set(key, "", CACHE_NULL_TTL, TimeUnit.MINUTES);
            return null;
        }
        //6.存在，写入Redis
        stringRedisTemplate.opsForValue().set(key,JSONUtil.toJsonStr(shop), CACHE_SHOP_TTL, TimeUnit.MINUTES);
        //7.返回
        return shop;
    }

//    private boolean tryLock(String key){//获取锁
//        Boolean flag = stringRedisTemplate.opsForValue().setIfAbsent(key, "1", 10, TimeUnit.SECONDS);
//        return BooleanUtil.isTrue(flag);
//    }
//
//    private void unlock(String key){//释放锁
//        stringRedisTemplate.delete(key);
//    }
//
//    public void saveShop2Redis(Long id, Long expireSeconds) throws InterruptedException {
//        //1.查询店铺数据
//        Shop shop = getById(id);
//        Thread.sleep(200);
//        //2.封装逻辑过期时间
//        RedisData redisData = new RedisData();
//        redisData.setData(shop);
//        redisData.setExpireTime(LocalDateTime.now().plusSeconds(expireSeconds));
//        //3.写入Redis
//        stringRedisTemplate.opsForValue().set(CACHE_SHOP_KEY + id, JSONUtil.toJsonStr(redisData));
//    }
    @Override
    @Transactional//数据库操作的事务性
    public Result update(Shop shop) {
        Long id = shop.getId();
        if(id == null){
            return Result.fail("店铺id不能为空");
        }
        //1.更新数据库
        updateById(shop);
        //2.删除缓存
        stringRedisTemplate.delete(CACHE_SHOP_KEY + shop.getId());
        return null;
    }


    //实现附近商户功能
    @Override
    public Result queryShopByType(Integer typeId, Integer current, Double x, Double y) {
        // 1.是否需要根据坐标查询
        if (x == null || y == null) {
            // 不需要坐标查询，按数据库查询
            Page<Shop> page = query()
                    .eq("type_id", typeId)
                    .page(new Page<>(current, SystemConstants.DEFAULT_PAGE_SIZE));
            // 返回数据
            return Result.ok(page.getRecords());
        }
        // 2.计算分页参数
        int from = (current - 1) * SystemConstants.DEFAULT_PAGE_SIZE;
        int end = current * SystemConstants.DEFAULT_PAGE_SIZE;
        // 3.查询Redis, 按照距离排序， 分页  结果：shopId,distance
        String key = SHOP_GEO_KEY + typeId;
        GeoResults<RedisGeoCommands.GeoLocation<String>> results = stringRedisTemplate.opsForGeo() // GEOSEARCH BYLONLAT x y BYRADIUS 10 WITHDISTANCE
                .search(key,
                        GeoReference.fromCoordinate(x, y),
                        new Distance(5000),// 单位：米
                        RedisGeoCommands.GeoSearchCommandArgs.newGeoSearchArgs().includeCoordinates().limit(end)
                );
        // 4.解析出id
        if(results == null){
            return Result.ok(Collections.emptyList());
        }
        List<GeoResult<RedisGeoCommands.GeoLocation<String>>> list = results.getContent();
        if(list.size() < from) {
            // 没有下一页
            return Result.ok(Collections.emptyList());
        }
        // 4.1 截取从from到end的部分
        List<Long> ids = new ArrayList<>(list.size());
        Map<String, Distance> distanceMap = new HashMap<>(list.size());
        list.stream().skip(from).forEach(result -> {
            // 4.2 获取店铺id
            String shopIdStr = result.getContent().getName();
            ids.add(Long.valueOf(shopIdStr));
            // 4.3获取距离
            Distance distance = result.getDistance();
            distanceMap.put(shopIdStr, distance);
        });
        // 5.根据id查询shop
        String idStr = StrUtil.join(",", ids);
        List<Shop> shops = query()
                .in("id", ids).last("ORDER BY FIELD(id," + idStr + ")").list();
        for (Shop shop : shops) {
            shop.setDistance(distanceMap.get(shop.getId().toString()).getValue());
        }
        //6. 返回
        return Result.ok(shops);
    }
}




/*
@Override
    public Result queryByid(Long id) {
        String key = CACHE_SHOP_KEY + id;
        //1.从Redis查询商铺缓存
        String shopJson = stringRedisTemplate.opsForValue().get(key);
        //2.判断是否存在
        if (StrUtil.isNotBlank(shopJson)) {//ctrl + q,查看方法具体提示
            //3.存在，直接返回
            Shop shop = JSONUtil.toBean(shopJson, Shop.class);//用于将 JSON 字符串转换为指定类型的对象。
            return Result.ok(shop);
        }
        //判断命中的是否是空值
        if(shopJson != null){
            //返回一个错误信息
            return Result.fail("店铺信息不存在");
        }

        //4.不存在，根据id查询数据库
        Shop shop = getById(id);
        //5.不存在
        if(shop == null){
            //将空值写入Redis
            stringRedisTemplate.opsForValue().set(key, "", CACHE_NULL_TTL, TimeUnit.MINUTES);
            return Result.fail("店铺不存在");
        }
        //6.存在，写入Redis
        stringRedisTemplate.opsForValue().set(key,JSONUtil.toJsonStr(shop), CACHE_SHOP_TTL, TimeUnit.MINUTES);
        //7.返回
        return Result.ok(shop);
    }
 */